Sometime during the 16th century, an extended family of inbred cannibals allegedly haunted the road outside of Edenborough. They robbed, murdered, and ate people who passed by. The story goes that they did this for 25 years before people found out about it from a survivor, and then the king lead an army to root them out of their cave and kill them all.
How factual is this story?
Most evidence points to it being a story far more than truth. While the story is said to have taken place around the end of the 17th century (some versions claim the 15th century), there's no written evidence of it until 1775. It's found then in English broadsides and newspapers. Likely it was brought up as an English story to show, again, the supposed terrible nature of the Scots. Even "Sawney" is considered an almost characterized Scottish name. It's easy to say that there is some basis of truth simply because people being robbed along long forest roads is definitely accurate. As for the rest, it makes for a good story!